1. Field of the Invention
The present invention relates to a high frequency parallel strip line cable for transmitting a high frequency signal such as a microwave signal or the like, which has a frequency higher than about 800 MHz, and in particularly, to a triplate or multi-plate type high frequency parallel strip line cable comprising a circuit device part integratedly formed in a dielectric body of the high frequency parallel strip-line cable.
2. Description of the Related Art
FIG. 5 shows a small-sized conventional high frequency apparatus 50 using a conventional coaxial cable 53.
Referring to FIG. 5, inside the small-sized high frequency apparatus 50 such as a movable portable telephone or the like, which is installed within a case body for covering the high frequency apparatus 50, there has been conventionally used the small coaxial cable 53 as a transmission line for connecting a component with another component so as to transmit therebetween a high frequency signal such as a microwave signal or the like. In the case of FIG. 5, the coaxial cable 53 is provided for connecting an antenna 51 through a connector 54 with a circuit device of circuit substrate 52.
With advancement in performances of recent small-sized high frequency apparatuses, there have arisen the following problems:
(a) noises generated within the circuit devices of the small-sized high frequency apparatus influence operations of the high frequency apparatus; and PA1 (b) the reflection loss or the like is caused due to mismatching between impedances of the circuit devices. PA1 a strip-shaped dielectric body made of either an electrical insulating material having a flexibility or another electrical insulating material having a plasticity, said dielectric body composed of a pair of dielectric layers; PA1 a pair of thin-film-shaped earth conductors formed on both surfaces of said dielectric body so as to oppose to each other; PA1 a thin-film-shaped center conductor formed between said pair of dielectric layers in said dielectric body so as to be located between said pair of earth conductors; and PA1 a circuit device part formed between said pair of dielectric layers in said dielectric body so as to be electrically connected with said center conductor, thereby said parallel strip-line cable having either a flexibility or a plasticity. PA1 a strip-shaped main dielectric body made of either an electrical insulating material having a flexibility or another electrical insulating material having a plasticity, said main dielectric body composed of a pair of main dielectric layers; PA1 a pair of thin-film-shaped earth conductors formed on both surfaces of said dielectric body so as to oppose to each other; PA1 a thin-film-shaped center conductor formed between said pair of dielectric layers in said dielectric body so as to be located between said pair of earth conductors; PA1 a strip-shaped sub-dielectric body made of either an electrical insulating material having a flexibility or another electrical insulating material having a plasticity, said sub-dielectric body composed of a pair of sub-dielectric layers; PA1 a thin-film-shaped further earth conductor formed on an upper surface of said sub-dielectric body so as to oppose to said earth conductor; PA1 a circuit device part formed between said pair of sub-dielectric layers in said sub-dielectric body; and PA1 connecting means for electrically connecting said circuit device part with said center conductor, said connecting means being formed so as to penetrate said main and sub-dielectric bodies, thereby said parallel strip-line cable having either a flexibility or a plasticity.
In order to solve the above-mentioned problems, it may be conceivable to incorporate an additional circuit device such as a noise filter circuit, an impedance matching circuit, or the like into the high frequency apparatus. However, if the additional circuit devices were installed in the high frequency apparatus, the size of the high frequency apparatus would become larger. Thus, it has been difficult to adopt such an arrangement, in particular, in the small-sized high frequency apparatus such as a movable portable telephone.